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EP 0 681 317 B1 |
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EUROPEAN PATENT SPECIFICATION |
(45) |
Mention of the grant of the patent: |
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17.10.2001 Bulletin 2001/42 |
(22) |
Date of filing: 07.04.1995 |
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(54) |
Method for cleaning semiconductor wafers using liquefied gases
Verfahren zur Reinigung von Halbleiterscheiben mittels verflüssigter Gase
Procédé pour nettoyer des semi-conducteurs sous utilisation de gaz liquides
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Designated Contracting States: |
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DE FR GB IT NL |
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Priority: |
08.04.1994 US 225164
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Date of publication of application: |
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08.11.1995 Bulletin 1995/45 |
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Proprietor: TEXAS INSTRUMENTS INCORPORATED |
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Dallas
Texas 75265 (US) |
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Inventor: |
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- Paranjpe, Ajit P.
Plano, TX 75075 (US)
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(74) |
Representative: Schwepfinger, Karl-Heinz, Dipl.-Ing. |
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Prinz & Partner GbR
Manzingerweg 7 81241 München 81241 München (DE) |
(56) |
References cited: :
EP-A- 0 538 653 US-A- 5 013 366
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US-A- 4 695 327 US-A- 5 235 995
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- SOLID STATE TECHNOLOGY, vol. 35, no. 6, June 1992, pages 117-120, XP002048102 E. BOK
ET AL.: "Supercritical Fluids for Single Wafer Cleaning"
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates in general to the field of semiconductor processing and more
particularly to an improved method for cleaning semiconductor substrates using liquefied
gases.
BACKGROUND OF THE INVENTION
[0002] Cleaning the surface of semiconductor substrates is a critical step in the integrated
circuit fabrication process. Surface cleaning eliminates particulates and trace surface
contaminations such as organic and metallic impurities. Traditionally, these cleaning
techniques have been based almost entirely on chemical reagents, which selectively
remove the surface contaminants and particulates without attacking or chemically altering
the wafer surface. As the permissible concentrations of contaminants scale down with
increasing device integration density, these traditional "wet" cleans are becoming
increasingly supplanted by "dry" cleans which employ a vapor phase medium for the
clean. Wet cleaning techniques also suffer from the limitation that liquid cleaning
materials cannot penetrate the intricate topologies associated with the small geometries
encountered in modern integrated circuits. Dry cleans also enjoy an advantage that
they are compatible with the concept of integrated single wafer processing which emphasizes
the need to isolate the wafer from an uncontrolled ambient during the fabrication
sequence. In contrast, wet cleaning is performed at ambient pressure in an atmospheric
environment. Contamination of the wafer surface is more likely in such an atmosphere.
In addition, chemical waste generated by wet cleaning processes requires elaborate
and expensive waste management.
[0003] Considerable progress has been made in developing dry or vapor phase cleans that
are effective in removing some forms of contamination. In particular, vapor phase
cleans are effective in the removal of native oxides and organic impurities. However,
progress in the removal of metallic contaminants such as nickel, chromium, iron, zinc,
and generic particulates has been more modest. Wet cleaning steps are usually used
to remove these forms of contaminants.
[0004] Conventional wet cleaning systems use megasonic agitation in a solvent bath followed
by rinsing and spin drying to remove particulates and contaminants from the wafer
surface. Unless the particulates and contaminants can be volatilized, traditional
vapor phase processing is incapable of removing the particulates and contaminants.
Gas phase chemistries used to remove metallic contaminants must volatilize the impurities
for effective removal. Halogen gases are effective in removing trace quantities of
some metallic contaminants. O
2/O
3 can remove some organic contaminants and HF/alcohols can remove native oxide.
[0005] US-A-5 013 366 discloses a process for removing two or more contaminants from a substrate
in a single process. The substrate to be cleaned is contacted with a dense phase gas
at or above the critical pressure thereof. The phase of the dense phase gas is then
shifted between the liquid state and the supercritical state by varying the temperature
of the dense fluid in a series of steps between temperatures above and below the critical
temperature of the dense fluid. After completion of each step in the temperature change,
the temperature is maintained for a predetermined period of time in order to allow
contact with the substrate and contaminants and removal of the contaminants. At each
step in the temperature change, the dense phase gas possesses different cohesive energy
density or solubility properties.
[0006] The article "Supercritical Fluids for Single Wafer Cleaning" by E. Bok et al. in
Solid State Technology, Vol. 35, no. 6, June 1992, pages 117-120, describes a wafer
cleaning system that uses supercritical CO
2 as a cleaning fluid. A wafer is loaded between upper and lower blocks of a cleaning
chamber. The lower block is then raised until the chamber is sealed. CO
2 pressurized at approximately 5.51 MPa is then supplied through centrally positioned
orifices. During the cleaning cycle, the supercritical fluid is pulsated by a hydraulic
mechanism. Pressure is typically cycled between 5.51 and 8.27 MPa at a frequency of
25 to 50 Hz. A separate expulsion cycle is used less frequently, i.e. every one to
three seconds, to replenish the cleaning fluid with fresh fluid. The expulsion cycle
is effected by dropping the lower chamber block so a 2 µm gap is opened to atmospheric
pressure around the outer circumference of the cleaning chamber. Contaminant-carrying
fluid then rushes outward through passages into the exhaust system. The seal is then
reclosed and fresh fluid is admitted through inlet valves, which are centrally positioned
above and below the wafer chamber.
SUMMARY OF THE INVENTION
[0007] According to the present invention, a method for cleaning the surface of a semiconductor
substrate is provided that comprises the steps of claim 1. The wafer with the liquid
phase cleaning agent in contact with the surface to be cleaned may be agitated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] A more complete understanding of the teachings of the present invention may be acquired
by referring to the attached FIGURE wherein:
FIGURE 1 is a cross-sectional schematic illustration of a semiconductor processing
system.
DETAILED DESCRIPTION OF THE INVENTION
[0009] Referring to FIGURE 1, a semiconductor cleaning system indicated generally at 10
is illustrated. Cleaning system 10 comprises a cleaning chamber 12 and a load lock
wafer handler chamber 14. Cleaning chamber 12 functions to use the teachings of the
present invention to remove surface contaminants from the surface of a semiconductor
substrate 16 shown in FIGURE 1. Load lock wafer handler 14 functions to retrieve substrates
such as substrate 16 from cleaning chamber 12 and to route them to other semiconductor
processes without exposing substrate 16 to atmospheric contaminants. The pressure
within cleaning chamber is in part controlled by an evacuation pump 18. Similarly,
the pressure within load lock wafer handler chamber 14 is controlled by an evacuation
pump 20.
[0010] Semiconductor substrate 16 is held in a wafer chuck 18. Wafer chuck 18 is coupled
to a wafer chuck manipulator 20 through piezoelectric ultrasonic exciters 22 and 24.
Exciters 22 and 24 are electrically coupled to a megasonic exciter 26 which supplies
electrical signals to exciters 22 and 24 to cause wafer chuck 18 and semiconductor
substrate 16 to megasonically vibrate when exciters 22 and 24 are activated by megasonic
exciter 26. Wafer chuck manipulator 20 is movably coupled to chamber 12 such that
the semiconductor substrate 16 can be moved in a vertical direction in and out of
bath chamber 28. According to one embodiment of the present invention, wafer chuck
manipulator 20 is also able to rapidly spin wafer chuck 18 and substrate 16 during
the cleaning process. Wafer chuck 18 and substrate 16 may also be temperature controlled
in one embodiment by using an embedded heater in wafer chuck 18.
[0011] Bath chamber 28 is coupled to a gas source 30 through a control valve 32. Gas source
30 selectively introduces liquefied gas into the cleaning chamber 28. System 10 in
FIGURE 1 is illustrated as having a small quantity of liquefied gas indicated as 34
disposed within cleaning bath 28. The phase of the cleaning agent 34 is controlled
in part by the pressure within cleaning chamber 12 which is controlled by pump 18
and delivery pressure of gas source 30. The phase of cleaning agent 34 is also controlled
by controlling the temperature of bath chamber 28 and cleaning agent 34. A heating
element 36 is disposed as shown in the base of cleaning chamber 28. Heating element
36 is electrically coupled to a heater control unit 38. The temperature of the cleaning
bath chamber 28 is further controlled by circulating refrigerant into a refrigerant
passage 40. Refrigerant passage 40 is coupled by refrigerant lines 42 and 44 to a
refrigerant control unit 46. Refrigerant control 46 causes refrigerants such as liquid
nitrogen to be circulated through the base of cleaning bath 28 to rapidly reduce the
temperature of the cleaning agent 34.
[0012] Cleaning bath 28 is coupled to the chamber 12 through additional piezoelectric ultrasonic
exciters 48 and 50. Exciters 48 and 50 are electronically coupled megasonic exciter
26 and function in a similar manner to exciters 22 to megasonically agitate the cleaning
bath 28 and simultaneously megasonically excite the cleaning agent 34 disposed in
the bath 28.
[0013] As will be described herein, the system 10 functions to clean the surface of substrate
16 while cleaning agent 34 is in a liquid phase. During surface cleaning, the contamination
on substrate 16 becomes dissolved or suspended in cleaning agent 34. Cleaning agent
34 is then changed to a vapor phase by flash evaporation to remove the contaminants
that are dissolved or suspended in the cleaning agent. This flash-evaporation is caused
by rapidly dropping the pressure using pump 18 as the cleaning agent 34 is removed
using an exhaust pump 52 which is in direct communication with the interior of the
cleaning bath 28. This cleaning cycle may be repeated to ensure complete removal of
contaminants. In the case of multiple cycles, chamber 12 may not be fully evacuated
between cycles. The residual gases then fill the fine features in the topography of
substrate 16. These residual gases condense inside these fine features during the
next cycle when the fresh batch of liquefied gases is introduced. This ensures that
cleaning agent 34 is in intimate contact with the entire surface of substrate 16.
In conventional wet cleaning practice surface tension forces prevent cleaning agent
34 from entering the fine features on substrate 6. This prevents effective contaminant
removal from the inside of fine features on substrate 16.
[0014] In operation, a cleaning agent is introduced from gas source 30 through valve 32
into cleaning bath 28. Ordinarily, the cleaning agent is introduced in liquid phase
and the pressure within cleaning chamber 12 is kept at an appropriate pressure to
keep the cleaning agent 34 in a liquid phase. Alternatively, the gases may be introduced
in gaseous phase and the pressure in chamber 12, and temperature of chamber bath 28,
wafer chuck 18 and substrate 16 adjusted to condense the gases to a liquid phase to
form cleaning 34. Intimate contact between cleaning agent 34 and substrate 16 is ensured
even for the first cleaning cycle. The semiconductor substrate 16 is lowered into
the liquid cleaning agent 34.
[0015] The interface between the semiconductor substrate 16 and the cleaning agent 34 is
then agitated using a variety of methods. The wafer chuck 18 and the cleaning bath
28 are megasonically agitated using the piezoelectric ultrasonic exciters 22, 24,
48 and 50 as described previously. In addition, the wafer chuck handler 20 can be
rotated rapidly to spin the semiconductor substrate 16 within the liquid cleaning
agent 34. The rapid agitation of the cleaning agent and the semiconductor substrate
16 will cause the formation of gas if the temperature and pressure are close to the
phase transition conditions between the liquid phase and vapor phase for the particular
cleaning agent. The cleaning agent 34 can be kept close to the phase transition by
adjusting the temperature of cleaning agent 34 and the pressure within cleaning chamber
12. Agitation causes a small amount of gas to form which then enters the small topography
associated with the surface of semiconductor substrate 16. After the agitation ceases,
the gas returns to the liquid phase.
[0016] In this manner, the advantages associated with dry cleaning techniques using vapor
phase cleaning agents are combined with the advantages of the wet cleaning techniques.
The vapor phase cleaning agent is allowed to penetrate the intricate topography of
the semiconductor substrate surface and then return to a liquid phase to remove particulates
and contaminants.
[0017] The exhaust pump 52 and the pump 18 are then used to rapidly drop the pressure so
that the cleaning agent 34 flash-evaporates and the particulates and contaminants
are forcibly ejected from the surface of substrate 16. The flash-evaporation causes
the particulates to be ejected from the surface in such a manner that the particulates
are not redeposited onto the surface of substrate 16.
[0018] In the alternative, the heater control 38, heater element 36, refrigerant control
46, refrigerant channel 40 and heating elements within wafer chuck 18 can be used
to rapidly change the temperature of the substrate 16 to cause a similar sequential
condensation of the cleaning agent and flash-evaporation of the cleaning agent. Further,
the combined use of temperature and pressure cycling can cause even faster and complete
flash-evaporation of the cleaning agent 34 from the surface of the substrate 16.
[0019] According to an alternate embodiment of the present invention, the cleaning agent
34 is introduced in a liquid phase. The pump 18 and the heater element 36 are then
used to drop the pressure and increase the temperature within the cleaning chamber
12, respectively, to cause the cleaning agent to briefly change into the vapor phase.
This process enables the cleaning agent to penetrate the intricate topography of the
surface of the semiconductor substrate 16. After a short period of time, the pressure
within chamber 12 is once again raised and the refrigerant control 36 and refrigerant
channel 40 are used to return the cleaning agent to a liquid phase. In the liquid
phase, the cleaning agent 34 can be agitated as described previously. The cleaning
cycle is completed by the flash-evaporation of the cleaning agent 34 using the methods
described previously.
[0020] It should be understood that the amount of cleaning agent 34 shown in FIGURE 1 is
not to scale with respect to the dimensions of substrate 16. A very small amount of
cleaning agent is actually required to perform the cleaning operation of the present
invention. Only a thin film of liquid is needed to remove particulate contaminants
from the surface of the semiconductor substrate. The rapid evaporation of the cleaning
agent 34 will be greatly enhanced if only a minimum amount of cleaning agent is used.
[0021] The system can use a variety of cleaning agents 34 provided by gas source 30. For
example, for the removal of particulate matter, liquefied argon or nitrogen can be
used. Particulate removal by megasonic agitation or via spray cleaning using a liquid
depends primarily on the surface tension of the liquid, whether the molecules of the
liquid are polar or non-polar, and the pH of the liquid. Typically particulate removal
efficiencies are better for liquids with low surface tension and non-polar or alkaline
liquids. Lower surface tension liquids wet the particulates and this wetting action
lifts the particulate from the surface thereby reducing the adhesion between the particulate
and the surface. Surface tension decreases with increasing temperature and is zero
at the boiling point. Thus liquefied gases are more effective in particulate removal
than conventional liquid reagents especially if the megasonic agitation is performed
at temperatures approaching the boiling point. Thus liquefied gases are more effective
in particulate removal than conventional reagents especially if the megasonic agitation
is performed at temperatures approaching the boiling point. In addition, the two phase
(liquid/gas) flow conditions that accompany boiling can impart additional energy to
the wafer surface dislodging particulates. Thermophoretic forces also contribute to
particulate removal. Several non-polar (e.g. N
2, O
2, CO
2) or alkaline (e.g. NH
3) liquified gases are suitable for particulate removal.
[0022] For the removal of organic contaminants, liquefied carbon dioxide or any of the freon
family of gases can be used. A variety of other organic gases can also be used to
dissolve and remove organic contaminants. The system of the present invention can
also be used to remove metallic contaminants by using liquefied hydrochloric acid,
hydrofluoric acid or sulphur dioxide. Ionic dissociation of several acidic liquefied
gases (e.g. HCL, HB
E, HF, SO
3) is significant at cryogenic temperatures. In some cases such as for HCL the ionic
concentrations may be too high. Thus, it may be necessary to dilute or buffer the
liquefied gases with other inert liquefied gases or alkaline liquefied gases such
as ammonia. The use of these highly caustic compounds can be buffered by using liquefied
ammonia or other alkaline agents to balance the acidity of the cleaning agent. This
buffering will prevent the cleaning agent from attacking the internal surfaces of
cleaning chamber 12 and can be also used to carefully control the damage to the semiconductor
substrate 16 caused during the cleaning process.
[0023] An important technical advantage of the cleaning system 10 is the fact that the cleaning
utilizes a liquid phase cleaning operation but occurs in a controlled ambient environment.
Accordingly, the cleaning chamber 12 can be coupled through load lock wafer handler
14 to other atmospherically controlled processes. For example, load lock wafer handler
chamber 14 can be used to transfer semiconductor substrate 16 from the cleaning chamber
12 into a variety of other processes, including etch processes, rapid thermal processes,
or other cleaning processes such as plasma cleaning operations using ultraviolet light
and the like.
[0024] A further technical advantage of the present invention is the fact that it capitalizes
on the best attributes of both dry and wet cleaning operations. The system causes
a cleaning agent to cross the phase transition between gas and liquid during the cleaning
operation. The vapor phase is used to penetrate the intricate topographies of the
surface to be cleaned and the cleaning agent is then returned to the liquid phase
to cause the removal of the contaminants and particulate matter. The megasonic and
other agitation methods used in conventional wet cleans can be used in conjunction
with the system of the present invention when the cleaning agent used in the system
of the present invention is in the liquid phase. Further, the cleaning agent is flash-evaporated
to complete the process so that none of the cleaning agent or the contaminants remain
on the wafer and the wafer may be transferred to other processes.
[0025] Although the present invention has been described in detail, it should be understood
that various changes, alterations, substitutions and modifications may be made to
the methods described herein without departing from the scope of the present invention
which is solely defined by the appended claims.
1. A method for cleaning a surface of a semiconductor substrate (16) comprising the sequence
of steps of:
introducing a cleaning agent (34) into a cleaning bath (28) in a liquid phase;
bringing the surface of the semiconductor substrate (16) into contact with the liquid
cleaning agent (34);
causing the cleaning agent (34) to change to a vapor phase such that the cleaning
agent (34) can penetrate the topology of the surface of the substrate (16);
returning the cleaning agent (34) to a liquid phase; and
flash-evaporating the cleaning agent (34) and removing the evaporated cleaning agent
and contaminants removed from the surface of the substrate (16) from the cleaning
bath (28).
2. The method of claim 1, wherein the step of causing the cleaning agent (34) to change
phase comprises the step of agitating the cleaning agent (34) to cause portions of
the cleaning agent (34) to locally change to the vapor phase and to dislodge particulates
from substrate surface.
3. The method of claim 2, wherein the step of agitating the cleaning agent (34) comprises
the step of megasonically exciting the cleaning bath (28) and megasonically exciting
the semiconductor substrate (16).
4. The method of claim 2, wherein the step of agitating the cleaning agent (34) comprises
the step of rapidly spinning the semiconductor substrate (16) when the substrate (16)
is in contact with the cleaning agent (34).
5. The method of any preceding claim, wherein the step of causing the cleaning agent
(34) to change phase comprises the step of altering the pressure of the environment
of the cleaning agent (34) to cause the cleaning agent (34) to change to the vapor
phase.
6. The method of any of claims 1 to 4, wherein the step of causing the cleaning agent
(34) to change phase comprises the step of changing the temperature of the agent (34)
to cause the cleaning agent (34) to change to a vapor phase.
7. The method of any preceding claim, wherein the step of introducing a cleaning agent
(34) comprises the step of introducing a non-polar material into the cleaning bath
(28) to remove particulate matter from the surface of the substrate (16).
8. The method of any of claims 1 to 6, wherein the step of introducing a cleaning agent
(34) comprises the step of introducing a polar material into the cleaning bath (28)
to remove particulate matter from the surface of the substrate (16).
9. The method of any of claims 1 to 6, wherein the step of introducing a cleaning agent
(34) comprises the step of introducing a liquid acidic material buffered with an alkaline
material.
10. The method of any of claims 1 to 6, wherein the step of introducing a cleaning agent
(34) comprises the step of introducing liquid hydrofluoric acid buffered with ammonia.
11. The method of any of claims 1 to 6, wherein the step of introducing a cleaning agent
(34) comprises the step of introducing a liquid organic material.
12. The method of any preceding claim, wherein the step of causing the cleaning agent
(34) to change to a vapor phase further comprises causing the cleaning agent (34)
to momentarily change to a vapor phase by megasonically exciting the cleaning bath
(28) and megasonically exciting the semiconductor substrate (16).
1. Verfahren zum Reinigen einer Oberfläche eines Halbleitersubstrats (16), das die Folge
der Schritte umfaßt:
Einleiten eines Reinigungsmittels (34) in ein Reinigungsbad (28) in einer flüssigen
Phase;
Bringen der Oberfläche des Halbleitersubstrats (16) in Kontakt mit dem flüssigen Reinigungsmittel
(34);
Veranlassen, daß das Reinigungsmittel (34) in die Dampfphase wechselt, so daß das
Reinigungsmittel (34) in die Topologie der Oberfläche des Substrats (16) eindringen
kann;
Zurückführen des Reinigungsmittels (34) in die flüssige Phase; und
Schnellverdampfen des Reinigungsmittels (34) und Entfernen des verdampften Reinigungsmittels
und der von der Oberfläche des Substrats (16) entfernten Verunreinigungen aus dem
Reinigungsbad (28).
2. Verfahren nach Anspruch 1, bei dem der Schritt, während dem das Reinigungsmittel (34)
zu einem Wechsel der Phase veranlaßt wird, das Bewegen des Reinigungsmittels (34)
umfaßt, um Teile des Reinigungsmittels (34) zu einem lokalen Wechsel in die Dampfphase
zu veranlassen und um Partikel von der Substratoberfläche zu lösen.
3. Verfahren nach Anspruch 2, bei dem der Schritt des Bewegens des Reinigungsmittels
(34) den Schritt des megasonischen Erregens des Reinigungsbades (28) und des megasonischen
Erregens des Halbleitersubstrats (16) umfaßt.
4. Verfahren nach Anspruch 2, bei dem der Schritt des Bewegens des Reinigungsmittels
(34) den Schritt des schnellen Drehens des Halbleitersubstrats (16), wenn das Substrat
(16) mit dem Reinigungsmittel (34) in Kontakt ist, umfaßt.
5. Verfahren nach einem vorhergehenden Anspruch, bei dem der Schritt, während dem das
Reinigungsmittel (34) zu einem Phasenwechsel veranlaßt wird, den Schritt des Änderns
des Umgebungsdrucks des Reinigungsmittels (34) umfaßt, um das Reinigungsmittel (34)
zu einem Wechsel in die Dampfphase zu veranlassen.
6. Verfahren nach einem der Ansprüche 1 bis 4, bei dem der Schritt, während dem das Reinigungsmittel
(34) zu einem Phasenwechsel veranlaßt wird, den Schritt des Änderns der Temperatur
des Mittels (34) umfaßt, um das Reinigungsmittel (34) zu einem Wechsel in die Dampfphase
zu veranlassen.
7. Verfahren nach einem der vorhergehenden Ansprüche, bei dem der Schritt des Einleitens
eines Reinigungsmittels (34) den Schritt des Einleitens eines nichtpolaren Materials
in das Reinigungsbad (28) umfaßt, um Partikelmaterial von der Oberfläche des Substrats
(16) zu entfernen.
8. Verfahren nach einem der Ansprüche 1 bis 6, bei dem der Schritt des Einleitens eines
Reinigungsmittels (34) den Schritt des Einleitens eines polaren Materials in das Reinigungsbad
(28) umfaßt, um Partikelmaterial von der Oberfläche des Substrats (16) zu entfernen.
9. Verfahren nach einem der Ansprüche 1 bis 6, bei dem der Schritt des Einleitens eines
Reinigungsmittels (34) den Schritt des Einleitens eines flüssigen, säurehaltigen Materials,
das mit einem alkalischen Material gepuffert ist, umfaßt.
10. Verfahren nach einem der Ansprüche 1 bis 6, bei dem der Schritt des Einleitens eines
Reinigungsmittels (34) den Schritt des Einleitens von flüssiger Flußsäure, die mit
Ammoniak gepuffert ist, umfaßt.
11. Verfahren nach einem der Ansprüche 1 bis 6, bei dem der Schritt des Einleitens eines
Reinigungsmittels (34) den Schritt des Einleitens eines flüssigen organischen Materials
umfaßt.
12. Verfahren nach einem der vorhergehenden Ansprüche, bei dem der Schritt, während dem
das Reinigungsmittel (34) zu einem Wechsel in die Dampfphase veranlaßt wird, ferner
das Veranlassen des Reinigungsmittels (34) zu einem vorübergehenden Wechsel in die
Dampfphase durch megasonisches Erregen des Reinigungsbades (28) und durch megasonisches
Erregen des Halbleitersubstrats (16) umfaßt.
1. Procédé pour nettoyer une surface d'un substrat semiconducteur (16) comprenant la
séquence d'étapes consistant à:
introduire un agent de nettoyage (34) dans un bain de nettoyage (28) dans une phase
liquide;
amener la surface du substrat semiconducteur (16) en contact avec l'agent de nettoyage
liquide (34);
amener l'agent de nettoyage (34) à passer à un état de phase vapeur de sorte que l'agent
de nettoyage (34) peut pénétrer dans la topologie de la surface du substrat (16);
ramener l'agent de nettoyage (34) à un état de phase liquide; et
produire une évaporation flash de l'agent de nettoyage (34) et retirer l'agent de
nettoyage évaporé et les contaminants retirés de la surface du substrat (16), à partir
du bain de nettoyage (28).
2. Procédé selon la revendication 1, selon lequel l'étape consistant à amener l'agent
de nettoyage (34) à changer de phase comprend l'étape consistant à agiter l'agent
de nettoyage (34) pour amener des parties de l'agent de nettoyage (34) à passer localement
à l'état de phase vapeur et détacher des particules de la surface du substrat.
3. Procédé selon la revendication 2, selon lequel l'étape d'agitation de l'agent de nettoyage
(34) comprend l'étape consistant à exciter le bain de nettoyage (28) par voie mégasonique
et à exciter le substrat semiconducteur (16) par voie mégasonique.
4. Procédé selon la revendication 2, selon lequel l'étape d'agitation de l'agent de nettoyage
(34) comprend l'étape consistant à faire tourner rapidement le substrat semiconducteur
(16) lorsque le substrat (16) est en contact avec l'agent de nettoyage (34).
5. Procédé selon l'une quelconque des revendications précédentes, selon lequel l'étape
consistant à amener l'agent de nettoyage (34) à changer de phase comprend l'étape
consistant à modifier la pression de l'environnement de l'agent de nettoyage (34)
pour amener l'agent de nettoyage (34) à passer à l'état de phase vapeur.
6. Procédé selon l'une quelconque des revendications 1 à 4, selon lequel l'étape consistant
à amener l'agent de nettoyage (34) à changer de phase comprend l'étape consistant
à modifier la température de l'agent (34) pour amener l'agent de nettoyage (34) à
passer à l'état de phase vapeur.
7. Procédé selon l'une quelconque des revendications précédentes, selon lequel l'étape
d'introduction d'un agent de nettoyage (34) comprend l'étape d'introduction d'une
substance non polaire dans le bain de nettoyage (28) pour retirer la matière particulaire
de la surface du substrat (16).
8. Procédé selon l'une quelconque des revendications 1 à 6, selon lequel l'étape d'introduction
d'un agent de nettoyage (34) comprend l'étape consistant à introduire une substance
polaire dans le bain de nettoyage (28) pour retirer la matière particulaire de la
surface du substrat (16).
9. Procédé selon l'une quelconque des revendications 1 à 6, selon lequel l'étape d'introduction
d'un agent de nettoyage (34) comprend l'étape consistant à introduire un milieu liquide
acide tamponné avec une substance alcaline.
10. Procédé selon l'une quelconque des revendications 1 à 6, selon lequel l'étape consistant
à introduire un agent de nettoyage (34) comprend l'étape consistant à introduire de
l'acide fluorhydrique liquide tamponné avec de l'ammoniac.
11. Procédé selon l'une quelconque des revendications 1 à 6, selon lequel l'étape d'introduction
d'un agent de nettoyage (34) comprend l'étape consistant à introduire une substance
organique liquide.
12. Procédé selon l'une quelconque des revendications précédentes, selon lequel l'étape
consistant à amener l'agent de nettoyage (34) à passer à un état de phase vapeur comprend
en outre le fait d'amener l'agent de nettoyage (34) à passier temporairement à l'état
de phase vapeur par excitation mégasonique du bain de nettoyage (28) et par excitation
mégasonique du substrat semiconducteur (16).